The present invention relates to a new and improved construction of insulation removal apparatus for the partial removal of an end section of an insulation sheathing or covering of an electrical conductor or the like, which apparatus is of the type comprising a thrust rod arranged to be axially displaceable in a housing and acting against the restoring force of a spring, and a holder clamp operatively connected with the thrust rod.
In German patent No. 1,083,881 there is disclosed to the art an insulation removal apparatus for electrically insulated conductors or lines, wherein two cutters or knives which are pivotably mounted towards one another at a housing and equipped with stops or impact members are retained by a bushing or sleeve. These cutters are opened by means of a piston rod mounted to be axially displaceable in the housing. The piston rod possesses an enlarged or reinforced portion at one end and is exposed to the tension of a spring. The wire from which the insulation is to be removed is introduced between both of the cutters, which thereafter are retracted due to the force of the spring which is effective at the piston rod, and thus such cutters are tightly pressed against the insulating sheathing or jacket. After one or two rotations of the housing the cutters have cut-through the insulation, whereafter, by axially withdrawing the insulation removal apparatus there can be simultaneously withdrawn from the conductor core the insulating jacket which is to be removed.
In Swiss patent No. 567,820 there is disclosed equipment for removing an end section of a plastic sheating or covering of an electrical conductor or wire wherein a clamping device provided with movable clamping jaws is arranged at a housing. The movable clamping jaws can be actuated by a rotatable rod through the intermediary of an eccentric. There is also provided a cutter device having two cooperating cutters or knives which are activated by means of a traction or pull rod arranged to be axially displaceable in the housing and energized by electromagnets, in such a manner that owing to the provision of suitable guide rails the cutters which cut-through the plastic sheathing or jacket are shifted towards one another, and thus the cut end section of the insulation sheathing can be withdrawn in axial direction from the fixedly clamped wire or conductor.
There is also known from German patent publication 1,515,503 a pneumatic device for the removal of the electrical insulation from a wire or conductor, wherein a shaft driven by a rotor is arranged in a housing. Mounted upon the shaft is an axially displaceable, conical piston. When the insulation removal device of this prior art patent is placed into operation, two levers, each tiltable about a pivot point and equipped with a cutting knife and a wire guide, rotatably close about the introduced conductor. Hence, due to the prevailing cutting pressure either the lacquered or enamelled electrical insulation is removed or a plastic sheathing is cut to the region of the stranded wires of the conductor and such is then subsequently withdrawn.
The heretofore discussed prior art equipment for the removal of insulation from electrical conductors or the like as well as other conventional, here not further described insulation removal tools, such as for example insulation removal clamps or the like, during the insulation removal operation partially damage and deform the insulation which remains upon the conductor and produce an undesired, irregular insulation-cutting edge, and additionally, such tools possess relatively large constructional size at the clamping- and cutting region. Hence, the fields of application of such prior art equipment is therefore limited.
According to a still further known technique for the removal of plastic sheathing or insulation covering at electrical conductors, the sheathing is fused down to the stranded wires of the conductor by means of a heated loop or the like. Thereafter, the cut insulation end is withdrawn. With this technique there is the considerable danger or damaging the conductor, especially when the wire or conductor ends are closely situated. Moreover, during the fusing or melting operation there are developed deleterious fumes or vapors and the insulation which remains on the conductor, also with this prior art technique, exhibits an irregular cut- or separation edge.